Container with pre-coated drain corner



Nov. 2, 1965 G. o. scHRoEDER 3,215,050

CONTAINER WITH PRE-COATED DRAIN CORNER Filed Nov. 18, 1963 www & fi;

BY m/@fw United States Patent O 3,215,050 CONTAINER WITH PRE-CATED DRAIN CORNER George Oscar Schroeder, Palatine, Ill., assignor to American Can Company, New York, N.Y., a corporation of New Jersey Filed Nov. 18, 1963, Ser. No. 324,274 Claims. (Cl. 9.3-36) This invention relates to liquid-tight containers and more particularly it relates to a container construction having improved liquid barrier and strength characteristics, and a method for producing this construction.

Because of their relatively low cost, liquid-proof fibre containers have become quite popular for marketing such products as milk, fruit juices, non-carbonated beverages, and other similar liquids. The structural requirements for containers of this type are rather rigid .in that they must be liquid-tight to prevent leakage, durable to withstand a great deal of handling between the time of manufacture and actual use and, where the product contained therein is a comestible for human consumption, they must also maintain the product in a sterile and uncontaminated condition.

Generally, the above requirements have been fairly Well met by the conventional waxed fibre or paperboard containers; however, it has been found that such containers are particularly susceptible to softening and subsequent leakage at the corners thereof and particularly at that corner which is known in the art as the drain corner. During fabrication of wax fibre containers, an interior wax coating is applied within the container and the container is subsequently inverted to allow the excess wax from the coating to drain out of the interior of the containers through a pour hole located at one corner of the container. The drain corner is that corner which is opposite the pour hole corner, and when the container is inverted into drain position to allow the excess wax to pour out through the pour hole corner, the wax drains away from the drain corner. Although the drain corner of the container is subjected to substantially the same interior heat as the other corners of the container, the wax itself quickly drains away from the drain corner and that wax coating which remains at the drain corner tends to soak into the fibre, thus leaving very little or no wax surface coating on the inner surface at the drain corner. Consequently, this drain corner is highly susceptible to softening when filled with liquid products and it is very likely that if leakage is to occur in the container, it will occur at the drain corner.

An object of the present invention, therefore, is to provide an improved container construction wherein the problem of differential wax absorption at the drain corner is overcome.

Another object of the present invention is to provide a liquidproof container having improved strength characteristics.

Another object of the present invention is to provide a liquidproof container construction wherein the softening problems at the corners, which were encountered in prior art forms of containers, are overcome.

Another object of the present invention is to provide a method for manufacturing an improved strength liquidproof container which is not susceptible to softening and/ or leakage at the drain corner.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred ernbodiment thereof.

The foregoing objects are accomplished by coating that corner of the container blank which is to form the drain corner when the container is subsequently erected and assembled. The coating material is relatively wax-impermeable material which tends to inhibit the undesirable wax impregnation of the drain corner. The coating materials used to coat the drain corner may be varied, however, they must be compatible with the wax coating to be subsequently applied in order to avoid aking of the wax and also they must be suitable for preventing complete wax impregnation of the drain corner with accompanying dry-waxed or exposed fibre inner container surface.

Referring to the drawing:

FIG. l is a perspective view of a container constructed in accordance with the present invention;

FIG. 2 is a plan view of one form of body blank used in construction of the container illustrated in FIG. l;

FIG. 3 is a perspective view of the body blank illustrated in FIG. 2 assembled into a tubular container body configuration;

FIG. 4 is a sectional view illustrating one suitable means for applying a wax coating to the interior of the container shown in FIG. l;

FIG. 5 is a view partly in section of one means for draining the excess wax from the interior of a container such as illustrated in FIG. l; and

FIG. 6 is a transverse sectional view of the container taken substantially along line 6-6 of FIG. l.

The configuration of the container illustrated in FIG. l is a well-known type, being of the general character of the container disclosed in U.S. Patent No. 2,085,979, issued to John E. Hothersall. Briefly described, this type of container generally designated 20, comprises an elongated tubular body, generally designated 22, preferably of square or rectangular cross-section, top and bottom end closures 24 and 26 respectively secured to the tubular body, and a hinged plug closure element 28 closing a pour hole at one corner of the top end 24. The body 22 is formed from a single blank which is folded with its opposite ends overlapping to form a side seam 30. The top and bottom margins of the body are neckedin as shown at 32 and 34, respectively, and arel then folded over the edges of the end closures 24 and 26 to form reinforced end seams 36, 36.

FIG. 2 illustrates the body blank 38 from which the tubular container body 22 can be constructed. The blank 33 is formed of ordinary fibre or paperboard stock and is provided with appropriately spaced parallel fold lines 40 which define therebetween those portions of the blank which will form the side walls of the con tainer body 22 when it is erected. The fold lines 40 extend parallel to opposite side edges 42 and 44 of the body blank 38. The blank is also provided respectively with generally parallel upper and lower edges 46 and 48. A pair of parallel score lines 50, 50 extend between the side edges 42 and 44 at a point spaced inward from the inner and lower edges 46 and 4S. Thus, an upper margin 52 is formed between the upper edge 46 and the transverse line 50 and a similar lower margin 54 is formed between the lower edge 48 and the transverse score line 50; these margins 52 and 54 respectively forming the necked-in portions 32 and 34 when the body blank is subsequently erected into a completed container.r Strips 56, 56 of adhesive, preferably of the hot-melt variety are applied at the extreme top and bottom edges of the blank 38 which correspond to the folded-over portions of the end Y seams 36 to provide the means for-securing the end a tubular configuration, one of the fold lines 40, which is to form the drain corner of the assembled container body, is coated with a coating material 60 as shown in FIGURE 2. The coating material 60 extends the full length of the drain corner fold line 40 but preferably terminates at the point where the fold line meets the upper and lower adhesive strips 56. It is, of course, possible for the coating material 60 to extend across the adhesive materials 56, provided that the coating material is formulated of a substance which is compatible with the adhesive material used. There are several materials which are suitable for use as the coating 60, but these materials must exhibit three specific characteristics; namely, they must be substantially wax-impermeable, they must be compatible with the wax ycoating which is to be applied to the interior of the container to thereby avoid wax flaking, and they must be exible enough to withstand the scoring and the bending encountered in formation of the necked-in portions. Polyethylene emulsions are the preferred coatings for the material 60, however, butyl rubber emulsion coatings, wax compatible latex coatings such as neoprene latex, and dispersion coatings such as ethylene-vinyl acetate are also suitable. There are numerous ways that the coating 60 can be applied and two known techniques which have proven satisfactory in practice are spraying and roller coating.

After the body blank 38 has been coated with the coating material 60, it is assembled into a tubular configuration as shown in FIG. 3. Subsequently, top and bottom end closures 24 and 26 are attached to the container body 22 to convert the body into the completed container 20. These top and bottom end closures may be attached by suitable methods known in the art, one such suitable method being that described in U.S. Patent No. 2,555,315, issued to J. P. Carroll. When the top closure 24 having a pour hole and hinged plug closure therein is attached to the tubular container body 22, it is imperative that the pour hole be located directly opposite the coated drain corner. This pour hole orientation is critical since the corner opposite the drain hole corner is the one from which the wax drains lirst and hence it is necessary that this corner, nominally called the drain corner, be the one that is coated with the coating material 60. lt is, of course, possible to coat all of the parallel fold lines 40 with the coating material 60 and if this expedient is adopted, orientation of the top closure 24 becomes unimportant since all corners are coated and thus any one of them can suitably serve as the drain corner.

After the container 20 has been completely erected and assembled, the hinged plug closure 28 is opened and the container is coated with wax either interiorly or interiorly and exteriorly by some suitable wax-applying means. One such means is shown in FIG. 4 wherein the container 20 is immersed in a bath of hot molten Wax 62, such as paralin, which is contained in a reservoir or tank 64. This wax-dipping operation produces both anr inner and an outer wax coating on the container 20. lf it is desired to have only an interior wax coating, a waxilushing operation can be used.

No matter whether the container is waxed on its interior surfaces by a wax-flushing operation or by a wax-dipping operation such as is shown in FIG. 4, it is necessary that the excess wax on the interior of the container be drained out through the container pour hole. Suitable means for accomplishing such drainage is shown in FIG. 5 wherein the container 20 is mounted within a bias rack 66 mounted on the wall of a tank or reservoir 68. As can be seen from FIG. 5, when the container 20 is being drained, the pour hole corner is located closest to the interior of the reservoir 68 while the drain corner is spaced furthest away. Such an arrangement tends to promote drainage of the interior wax through the pour hole. However, it will also be appreciated that when the container 20 is located in such an orientation, the interior wax 62 tends to drain quickly away from the drain corner 'toward the pour-hole corner and consequently the heat from the interior wax tends to cause the light coating of wax which was applied to the drain corner to soak into the bre layer of the container. This tendency to soak into the fibre is counteracted by the drain-corner coating material 60 which inhibits wax penetration of the fibre and thus assu-res that a satisfactory interior wax coating will be present at the drain-corner area.

FIG. 6 illustrates, in cross-section, the container construction after the waxing and draining opera-tions have been completed. It will be sen thatthe main fibre layer of the container, as formed by the body blank 38 isprovided with both an interior and an exterior wax coating 62. The location of the pour hole is indicated'V at 70 and it will be seen that the drain corner as protected by the coating 60 is located directly opposite the pour hole corner. Since the coating material 60 at the drain corner has prevented wax impregnation of It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and the steps of the method herein described without departing from the spirit and4 scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim: 1. A method of forming a liquid-tight container comprising the steps of:

providing a container body blank with longitudinally extending fold lines which are t-o form to corners of the subsequently erected container body; applying a stripe of wax impermeable material along at least one of said fold lines; erecting said container body blank into a tubular container body; I securing an imperforate bottom end closure to one end of said tubular container body; orienting a top end closure having a pour hole therein with said pour sole being diagonally opposite said striped corner; securing said top end closure to said tubular container body With said pour hole maintaining said orien tation; introducing a molten wax coating through said pour hole to coat the interior surfaces of said container; and draining the excess molten wax from said container whereby a smoothand continuous wax Coating will remain adhered to the interior of said container, and preventing said wax from soaking into said container body beneath said wax impermeable material, thus rendering said container liquid-tight. 2. A method as dened in claim 1 wherein said stripe of wax impermeable material is applied to only one corner.

3. A method of producing a liquidproof wax fibre container comprising the steps of:

forming a bre container body blank; producing longitudinally extending fold lines in said body blank; coating the upper and lower margins of said body blank with. an adhesive material;

applying a narrow strip of a Wax impermeable coating to one of said longitudinal fold lines, with said coating extending only a short distance transversely of said fold line;

folding said body blank into a tubular container body conguration with said fold lines forming the corners of said container body and said coating being on the interior thereof;

securing an imperforate lower end closure to the lower end of sai-d container body by means of said lower margin adhesive material;

orienting an u-pper end closure having a pour hole therein within the upper end of said container body, said pour hole being located diagonally opposite said coated inner corner;

securing said upper end closure, in its oriented position, to the upper end of said container body by means of said upper margin adhesive material;

introducing molten wax through said pour hole to coat the interior surfaces of said container; and

draining the excess molten wax through said container Ipour hole to thus leave a continuous wax coating on the interior of said container covering both said ibre and said wax impermeable coating and preventing the wax from soaking into said bre beneath the wax impermeable coating.

4. A method as defined in claim 3 wherein said wax 5 impermeable coating is applied by spraying it onto said body blank.

5. A method as defined in claim 3 wherein said Wax impermeable coating is applied by roller coating it onto said body blank.

References Cited by the Examiner UNITED STATES PATENTS FRANK E. BAILEY, Primary Examiner.

FRANKLIN T. GARRETT, BERNARD STICKNEY,

Examiners. 

1. A METHOD OF FORMING A LIQUID-TIGHT CONTAINER COMPRISING THE STEPS OF: PROVIDING A CONTAINER BODY BLANK WITH LONGITUDINALLY EXTENDING FOLD LINES WHICH ARE TO FORM TO CORNERS OF THE SUBSEQUENTLY ERECTED CONTAINER BODY; APPLYING A STRIPE OF WAX IMPERMEABLE MATERIAL ALONG AT LEAST ONE OF SAID FOLD LINES; ERECTING SAID CONTAINER BODY BLANK INTO A TUBULAR CONTAINER BODY; SECURING AN IMPERFORATE BOTTOM END CLOSURE TO ONE END OF SAID TUBULAR CONTAINER BODY; ORIENTING A TOP END CLOSURE HAVING A POUR HOLE THEREIN WITH SAID POUR SOLE BEING DIAGONALLY OPPOSITE SAID STRIPED CORNER; SECURING SAID TOP END CLOSURE TO SAID TUBULAR CONTAINER 